DE102008009201B4 - Method for controlling a drive train and drive train for a motor vehicle - Google Patents

Abstract

A method of controlling a powertrain (10) of a motor vehicle, comprising - an internal combustion engine (12) having an engine output shaft (14) adapted to apply a torque Mv to the powertrain (10); A switchable separating device (K2, 38; 40), which is connected to the motor output shaft (14) in rotationally driving connection, with which a part of the drive train (10) leading to drive wheels (26) of the motor vehicle can be separated from the internal combustion engine (12) a coupling element (36) arranged in the torque transmission path, having an input side (36a) and an output side (36b) coupled thereto with a play, - an electric machine (18) which drives the drive train (10) under predetermined operating conditions with a torque Me for closing the game can act on the coupling element (36), characterized in that - the play-related coupling element (36) in the torque transmission between the motor output shaft (14) and the separating device (K2, 38, 40) arranged and the internal combustion engine (12) with open separating device (K2 , 38; 40) is decoupled from the drive wheels (26), wherein the electrically generated torque Me Verbrennungsmot or on the side of or at the separating device (K2, 38; 40) is introduced into the drive train and wherein the electrically generated torque Me is opposed to the internal combustion engine generated torque Mv.

Description

The invention relates to a method for controlling a motor vehicle drive train according to the preamble of claim 1 and a drive train according to claim 7.

A generic method is already with the EP 1 590 576 B1 known. There, a motor vehicle drive train is described, comprising an internal combustion engine whose engine output shaft can load the drive train; a gear change transmission and a starting clutch arranged between the internal combustion engine and the transmission device, wherein a plurality of drive train components are coupled with play. The drive train is operated under predetermined conditions in a first operating mode in which the internal combustion engine moves the motor vehicle against the resistances directed against a movement of the motor vehicle, wherein the play is closed in the load direction predetermined by the direction of rotation of the motor output shaft. To achieve a high degree of operational reliability and a good ride comfort there is proposed to operate the drive train outside the first operating mode under predetermined conditions in a second operating mode in which a first load is introduced into a drive train section, which causes the game closed on the output side of this load introduction point is or remains closed, this first load being such that it would not be sufficient to overcome the opposition of the movement of the motor vehicle in the plane resistances. In this case, a starter generator load the drive train under predetermined conditions so that the game in the drive train on the output side of this load introduction point is closed or remains closed. Thus, when starting the engine-driven starter generator to initiate a rectified to the internal combustion engine, driving torque into the vehicle drive train, whereby existing in the drive train game can be closed before the rolling of the vehicle and a start-up thus fails.

It is known from the above-described problems detached that occurring in a vehicle driveline game leads to increased noise and increased wear, whereby the life of the playfully engaged components is greatly reduced and a faster replacement is required. This relates in particular in the torque transmission path between an internal combustion engine and a gear change components arranged components. For example, occurs at the junction of components that are connected by means of a pluggable toothing, in principle, a certain backlash on. This backlash occurs especially at no load engine idling negative in appearance, since in this operating condition of the average, output from an engine engine torque is very low and superimposed with ignition-related rotational nonuniformities, which leads to constant edge changes at the junction.

By contrast, such a high-frequency edge change does not occur when driving, since the relatively high mean torque of the internal combustion engine does not lead to a change of direction due to the superimposed irregularity. The rarely occurring in comparison to idle operation edge change due to train-thrust transitions do not lead to approximately comparable wear.

Starting from this problem, it is an object of the invention to provide a method for controlling a vehicle drive train and Fahrezugantriebsstrang with which wear of play-affected powertrain components can be reduced.

These objects are achieved by the method according to claim 1 and by the drive train according to claim 7. The dependent claims describe advantageous embodiments and further developments of the invention.

According to the first aspect of the invention, a method is proposed for controlling a drive train of a motor vehicle, comprising an internal combustion engine with an engine output shaft, which can act on the drive train with a torque Mv; a switchable disconnecting means connected to the engine output shaft for disconnecting a part of the drive train leading to drive wheels of the motor vehicle from the internal combustion engine, a coupling element arranged in the torque transmission path having an input side and an output side coupled thereto with a backlash and an electric machine the drive train under predetermined operating conditions with a torque Me can act on the coupling element to close the game. Assuming that the play-bearing coupling element is arranged in the torque transmission path between the engine output shaft and the separating device and the internal combustion engine is decoupled from the drive wheels with the separating device open, it is proposed to introduce the electrically generated torque Me from or on the separating device into the drive train the engine torque generated Mv, d. H. the moment driving the vehicle, is opposite.

The method can be applied to a conventional vehicle with a purely internal combustion engine drive. For this purpose, a relatively compact electrical machine with a torque is already suitable, which is in the order of magnitude of the idling of the engine superimposed torsional vibration. Of course, the method can also be applied to a hybrid vehicle, wherein the electric machine is dimensioned correspondingly larger in order to drive the vehicle at least temporarily alone or in conjunction with the internal combustion engine.

By the proposed method can be avoided in the internal combustion engine and the drive train decoupled drive wheels occurring in the drive train on the at least one switching element alternating loads, in particular edge changes, by the input and output side of the coupling element in a permanent by the action of the introduced electrically generated torque mutual attachment. In this way, a wear occurring at the play-affected drive train components wear can be significantly reduced.

The separator may be located at any position in front of the drive wheels within the drive train. In a particularly advantageous embodiment, the separating device is formed by the elements involved in a gearshift transmission for displaying the neutral position, wherein the transmission is in the neutral position for carrying out the method. The separating device can also be represented by a switchable friction or form-locking coupling, which is arranged in the drive train between the internal combustion engine and the transmission or at a position downstream of the transmission.

Advantageously, the amount of the electrically generated torque Me is selected such that torsional vibration moments occurring in the drive train can at least be compensated. Although a significantly exceeding amount of the torque Me would be possible in principle in the context of the method, but would result in an increase in its amount of rough running of the internal combustion engine, which would not be desirable in practice.

With further advantage, the amount of electrically generated torque Me is time-independent. It is therefore not absolutely necessary to constantly adjust the electrically impressed moment Me in terms of magnitude and direction to the internal combustion engine torsional vibration moment. As a result, complex control systems for implementing the method can be omitted.

According to a preferred variant, the electrically generated torque Me is impressed as regenerative torque in the drive train, whereby a part of the mechanical, provided by the engine energy is converted by the electric machine into electrical energy and these are fed to a switched electrical load, such as the vehicle control or for charging an energy storage, z. B. a low-voltage vehicle battery or an electric driving battery can serve.

However, as an alternative to the regenerative mode of operation of the electric machine, it is also possible to generate the electrically generated torque Me as a motor torque in the direction of rotation opposite to the output shaft of the internal combustion engine and to emboss it in the drive train. The energy required for this purpose can be taken to one of the aforementioned energy storage.

According to the second aspect of the invention, there is provided a powertrain for a motor vehicle for performing the method of any one of claims 1-6, the powertrain including an internal combustion engine having an engine output shaft capable of applying torque Mv to the powertrain; a switchable disconnecting means connected to the engine output shaft for rotationally driving a part of the power train leading to the drive wheels of the motor vehicle, a coupling element disposed in the torque transmission path between the engine output shaft and the disconnecting means having an input side and a play coupled thereto Output side, an electrical machine that can act on the drive train at predetermined operating conditions with a torque Me for closing the game on the coupling element, wherein the torque Me combustion engine side of or on the separator is introduced into the drive train. Furthermore, the drive train comprises control means which, when the internal combustion engine is running and the separating device is open, can actuate the electric machine for a predeterminable time period to deliver a torque Me directed counter to the engine torque Mv.

According to an advantageous embodiment, it is provided to form the electric machine as a motor generator, whereby it can operate both motor, thus driving, as well as regenerative, so braking. Such a If necessary, the motor generator can be used to start the internal combustion engine, generate electricity and drive the vehicle.

Advantageously, the separating device is formed within a arranged in the drive train speed change gear.

A particularly effective application of the method is in a coupling element designed as a coupling element, which may be formed within a component or between two components of the drive train.

The invention will be explained by way of example with reference to the single figure.

In the figure is schematically a drive train 10 for a hybrid vehicle whose torque transmission path is an internal combustion engine 12 with an output shaft 14 , a downstream torsion damper 16 , a switchable clutch K1, designed as a motor generator electric machine 18 , another switchable clutch K2 and a gear change transmission 20 comprising, of which the drive torque via an output shaft 22 and a differential 24 on vehicle wheels 26 is transmitted. The vehicle can, with the clutch K2 closed, at least temporarily by one of the electric machine 18 generated torque Me alone or with additionally closed clutch K1 solely by a torque Mv from the engine 12 or in conjunction with the electric machine 18 are driven. The clutches K1, K2 can be constructed as form-fitting or as friction clutches, wherein in the present case the clutch K1 is preferably designed as a form-locking coupling, particularly preferably as a dog clutch and the clutch K2 to enable a comfortable starting operation as a friction clutch.

The engine output shaft 14 of the internal combustion engine 12 is with the input side 16a of the torsion damper 16 coupled, this to improve the smoothness of the engine 12 over a usual flywheel 16d features. The exit side 16b of the torsion damper 16 is in this example without a separate flywheel, as it is known from a dual mass flywheel, carried out and torsion springs 16c with the input side 16a connected.

The electric machine 18 includes a rotationally fixed to the rotating components of the drive train 10 arranged stator 18a and and a rotatably mounted rotor 18b in the example directly in the torque transmission path of the drive train 10 is arranged. It is alternatively possible, the torque of the electric machine 18 via a gear or belt drive in the drive train 10 initiate. The stator 18a carries in a known manner a coil winding, which via a vehicle electrical system 28 by means of one of a control unit 30 controlled inverter 32 is supplied with electrical energy or by which energy generated in generator operation can be fed into the electrical system. The control unit 30 communicates with the control of the electrical machine 18 with a superordinate powertrain or vehicle control 34 which information about the operating state of the internal combustion engine via sensors not shown here graphically 12 , the clutches K1, K2, of the gearbox 20 and other powertrain components receives and to control the drive train 10 can evaluate.

It can be seen that with the clutch K1 closed the rotor 18b the electric machine 18 with the exit side 16b of the torsion damper 16 is operatively connected and acts as a secondary flywheel. The construction of the electric machine 18 is irrelevant in the light of the present invention, this can be designed both as an external rotor and as an internal rotor, but a defined moment of inertia can be represented by an external rotor with a relatively short compared to an internal rotor length. On the other hand, due to space constraints quite an internal rotor can be useful, as shown in the figure.

The rotary driving connection between the torsion damper and the separating clutch K1 is designed as a spline, which is a coupling element 36 forms and being the exit side 16b of the torsion damper 16 or a component connected thereto as a hollow shaft section 36a with an internal toothing and the input side of the coupling K1 or a component connected thereto as a shaft portion 36b is designed with a cooperating external toothing. In this case, the corresponding teeth can also be designed in the reverse manner. The entrance page 36a and the exit side 36b of the coupling element 36 are coupled to each other with a game, as this usually occurs in such a spline. The playful coupling element 36 is therefore in the torque transmission path between the engine output shaft 14 and the clutch K2 ausgebild which on the internal combustion engine 12 opposite side of the electric machine 18 follows in Drehmomentübetragungsweg. The coupling element 36 however, it does not necessarily have to be formed between two drivetrain components but can also be realized within a single component for connecting two components of this component. The clutch K2 thus forms a separator 38 with an input side 38a and a home page 38b , in the open state or position of the internal combustion engine 12 from the drive wheels 26 is decoupled.

When the vehicle is stationary or rolling, the clutch K2 for a longer period than this for a normal gear change operation of the transmission 20 is required, is opened, then it can by the play-related coupling element 36 come to an undesirable noise in the form of rattles. In such an operating condition, the proposed method of controlling the powertrain 10 before, for a predetermined period by the electric machine 18 to generate a torque Me and this in the drive train 10 initiate, wherein the torque Me is opposed to the internal combustion engine torque Mv generated and whereby the game on the coupling element 36 is closed by the flank system fixed in one direction of rotation and thus a constantly changing flank of the toothed parts 36a , b is suppressed. In this case, the amount of the electrically generated torque Me for the duration of the process is preferably constant, ie time-independent and also chosen so that in this section of the drive train 10 occurring and mainly by the internal combustion engine 12 conditional torsional vibration moments can be compensated safely.

According to the embodiment is provided, the electric machine 18 operate at least for the duration of the process in their regenerative mode and to use the electrical energy gained thereby to charge an electrical energy storage or this directly an electrical load within the electrical system 28 supply. Alternatively, however, it is also possible to initiate the electrically generated torque Me as a motor torque in this Antriebsstrangabschnit.

Furthermore, instead of a separate clutch K2 or a separate separating element 38 also be provided in a separate drive train component integrated separating element. For example, this can be a separator 40 within the gearbox 20 be provided, which there by the elements involved in representing the idle position 40a , b is formed here, for example, as an engagement formation of a gear pair 40a , b is shown. To carry out the method described is merely instead of opening the clutch K2, the gear change transmission 20 transferred to the neutral position, whereby the running internal combustion engine 12 can also be decoupled from the drive wheels.

Claims (10)

Method for controlling a drive train ( 10 ) of a motor vehicle, which comprises - an internal combustion engine ( 12 ) with an engine output shaft ( 14 ), the powertrain ( 10 ) can act on a torque Mv; - one with the motor output shaft ( 14 ) switchable disconnecting device (K2, 38 ; 40 ), with which one to drive wheels ( 26 ) of the motor vehicle leading part of the drive train ( 10 ) of the internal combustion engine ( 12 ) can be separated, - a coupling element arranged in the torque transmission path ( 36 ) with an input side ( 36a ) and an output side coupled thereto with a game ( 36b ), - an electric machine ( 18 ), which is the powertrain ( 10 ) under predetermined operating conditions with a torque Me for closing the game on the coupling element ( 36 ), characterized in that - the play-related coupling element ( 36 ) in the torque transmission path between the engine output shaft ( 14 ) and the separating device (K2, 38 ; 40 ) and the internal combustion engine ( 12 ) with the separating device open (K2, 38 ; 40 ) of the drive wheels ( 26 ) is decoupled, wherein the electrically generated torque Me combustion engine side of or on the separating device (K2, 38 ; 40 ) is introduced into the drive train and wherein the electrically generated torque Me is opposed to the internal combustion engine generated torque Mv. Method according to claim 1, wherein the drive train ( 10 ) a gear change transmission ( 20 ) having an idling position, characterized in that the separating device ( 40 ) by the in the gear change transmission ( 20 ) elements representing the idling position ( 40a , b) is formed and that the transmission ( 20 ) is in the neutral position. A method according to claim 1 or 2, characterized in that the electrically generated torque Me in the drive train ( 10 ) can at least compensate for occurring torsional vibration moments. Method according to one of the preceding claims, characterized in that the amount of electrically generated torque, Me is time-independent. Method according to one of the preceding claims, characterized in that the electrically generated torque Me is impressed as a generator torque. Method according to one of the preceding claims, characterized in that the electrically generated torque Me is impressed as a motor torque. Powertrain ( 10 ) for a motor vehicle for carrying out the method according to one of claims 1-6, wherein the drive train ( 10 ) - an internal combustion engine ( 12 ) with an engine output shaft ( 14 ), which is the powertrain ( 10 ) can act on a torque Mv; - one with the motor output shaft ( 14 ) switchable disconnecting device (K2, 38 ; 40 ), with which one to drive wheels ( 26 ) of the motor vehicle leading part of the drive train ( 10 ) of the internal combustion engine ( 12 ) can be disconnected, - in the torque transmission path between the engine output shaft ( 14 ) and the separating device (K2, 38 ; 40 ) arranged coupling element ( 36 ) with an input side ( 36a ) and an output side coupled thereto with a game ( 36b ), - an electric machine ( 18 ), which is the powertrain ( 10 ) can apply a torque Me under predefined operating states, wherein their torque Me Me internal combustion engine side of or on the separating device (K2, 38 ; 40 ) in the drive train ( 10 ) and - control means ( 30 . 34 ), while the engine is running ( 12 ) and with the separating device (K2, 38 ; 40 ) the electric machine ( 18 ) for a predeterminable period for delivering a combustion engine torque Mv counteracted torque Me can control. Drive train according to claim 7, characterized in that the electric machine ( 18 ) is designed as a motor generator. Drive train according to claim 7 or 8, characterized in that the separating device ( 40 ) within one in the drive train ( 10 ) arranged gear change transmission ( 20 ) is trained. Drive train according to one of claims 7-9, characterized in that the coupling element ( 36 ) as splines within a component or between two components ( 16 . 18 ) of the drive train ( 10 ) is trained.

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